1. Field of the Disclosure
The present invention relates to a composition comprising, in a cosmetically acceptable carrier, at least one UV screening system, characterized in that it comprises:
(i) at least one screening agent of lipophilic 2-hydroxybenzophenone type;
(ii) at least one silicon-comprising s-triazine of formula (III) substituted by at least two alkylaminobenzoate groups.
2. Description of Related Art
It is known that light radiation with wavelengths of between 280 nm and 400 nm makes possible burning of the human epidermis and that rays with wavelengths more particularly of between 280 and 320 nm, known under the name of UV-B, cause erythemas and skin burns which may be harmful to the development of natural tanning. For these reasons, and also for aesthetic reasons, there is constant demand for means for controlling this natural tanning in order thus to control the colour of the skin; this UV-B radiation should thus be screened out.
It is also known that UV-A rays, with wavelengths between 320 and 400 nm, which cause browning of the skin, are liable to induce adverse changes therein, in particular in the case of sensitive skin or skin that is continually exposed to solar radiation. UV-A rays cause in particular a loss of elasticity of the skin and the appearance of wrinkles leading to premature ageing of the skin. They promote triggering of the erythemal reaction or amplify this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons, for instance conservation of the skin's natural elasticity, for example, people increasingly wish to control the effect of UV-A rays on their skin. It is thus desirable also to screen out UV-A radiation.
For the purpose of protecting the skin and keratin materials against UV radiation, antisun compositions comprising organic screening agents that are active in the UV-A range and in the UV-B range are generally used.
Lipophilic benzophenone derivatives are known to be photostable screening agents which absorb UV-A radiation and some of them, such as amino-substituted 2-hydroxybenzophenones, such as n-hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate, sold under the name Uvinul A+ by BASF, are highly effective.
UV-B screening agents which are particularly advantageous and which are widely used at the present time are lipophilic screening agents of the silicon-free 1,3,5-triazine type. They are described in Patent Applications EP-A-0 517 104, EP-A-0 570 838, EP-A-796 851 and EP-A-0 775 698. The derivative 2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine, sold in particular under the trade name “Uvinul T150” by BASF, is known in particular. These lipophilic screening agents active in the UV-B region exhibit the disadvantage of being solid at ambient temperature. Their use in antisun compositions brings about formulation restrictions, with a need to identify solvents which make it possible to correctly dissolve them.
Other advantageous UV-B screening agents used in antisun compositions at the present time are alkyl β,β-diphenylacrylate or alkyl α-cyano-β,β-diphenylacrylate; mention may be made of 2-ethylhexyl α-cyano-β,β-diphenylacrylate, also known as octocrylene. It is available commercially and is sold in particular under the name “UVINUL N 539” by BASF. These screening agents exhibit the advantage of being easy to formulate but their screening properties are relatively weak, which is reflected by high concentrations of use in order to obtain an advantageous level of UV screening.
Cinnamic derivatives, such as 2-ethylhexyl 4-methoxycinnamate or isoamyl 4-methoxycinnamate, are good solvents for UV screening agents which are difficult to dissolve in oils and exhibit good photoprotection properties in the UV-B region. These cinnamic derivatives have the disadvantage of exhibiting an inadequate photostability and of disrupting the photostability of the complete screening systems into which they are introduced.
Silicon-comprising s-triazines substituted by at least two alkylaminobenzoate or alkylaminobenzamide groups are known, in Applications EP 0 841 341 and EP 1 891 079, for their absorbing properties in the UV-B region. The Applicant Company, during its research studies, has found that not all of these silicon-comprising triazine compounds substituted by at least two alkylaminobenzoate groups, in particular those for which the alkyl chain comprises more than 10 carbon atoms, make it possible to obtain a satisfactory effectiveness in combination with UV-A screening agents.
It thus appears necessary to have available a system which extensively screens out UV-A and UV-B radiation and which is easy to employ in antisun compositions without the abovementioned disadvantages, namely to obtain a system which screens out UV-A and UV-B rays which is photostable, which has a high protection factor and which has good solubility in antisun formulations.
In point of fact, the Applicant Company has now just discovered, surprisingly, that, by combining at least one screening agent of lipophilic 2-hydroxybenzophenone type with a silicon-comprising s-triazine substituted by at least two alkylaminobenzoate groups of formula (III), the definition of which will be given later, it is possible to obtain a system which extensively screens out UV-A and UV-B radiation, and which is easy to employ in antisun compositions without the abovementioned disadvantages.
This discovery forms the basis of the present invention.